Discussion in 'Random Nonsense' started by cloasters, May 16, 2019.
Can anyone say weather this pertains to Monitors and Televisions?
It's now pretty hard if not impossible for a consumer to find a non-LED screen.
Plasma is gone. I'm not up on the new TV's is there another working technology?
Thanks George, I'm unsure if you spread light or cast shade but thanks.":O}
This article is constructed for sensationalism, not information.
Here are some basic facts:
The human eye is MUCH less sensitive to blue light than it is to green, or even red. We are roughly half as sensitive to red as to green, and roughly half as sensitive to blue as to red (so 1/4 of green sensitivity). Look around at our world (the natural one, not the one we've built) and you should instantly understand why this is true.
Under normal conditions, the blue light we receive with our eyes is limited by the fact that it is mixed in with other light that we are MUCH more sensitive to; under normal conditions, our natural reflexes will kick in and limit the amount of light we allow into our eyes (ALL light), so blue light specifically is never an issue.
BECAUSE we are so much less sensitive to blue light than to green, and BECAUSE we normally only ever see significant amounts of blue light from sources that are emitting in other frequency ranges as well, it becomes much easier to overexpose our eyes to blue light, if we are looking at a source that emits ONLY blue light. Note that this same statement applies to sources that emit only red light, but not to the same degree.
A lot of modern devices have, for some reason, taken to using blue lights as indicators. Since we have reduced sensitivity to blue light, that means the light SOURCE has to be significantly more intense than usual in order for us to SEE the same brightness.
So basically, don't spend all day staring at bright blue lights, and you'll be fine.
If you DO stare at blue lights a lot, think about replacing them with something that is NOT blue, or at least not ONLY blue. Cyan contains green and blue mixed together, is a LOT easier on the eyes, and still serves to get attention. Magenta is not such a good choice since it combines red and blue (the two colors we are least sensitive to), but is still better than pure blue.
Adjust your CRT/Monitor/TV for a normal white level and sane intensity and you should be fine. Also be aware that watching a TV in a fully darkened room may be the popular way to enjoy entertainment, but is an unnatural state and will result in increased eye strain unless the brightness is adjusted accoringly.
For what it's worth, this isn't a new issue. We had the same conversation when color CRTs were first a thing, and when fluorescents were first a thing. If plasma screens had lasted more than a decade and been more than a niche product, we'd've had the same conversation about them.
Now, having said all that, one place that SHOULD be addressed is the blasted "star-in-a-jar" headlights that are on modern cars. If you need headlights that bright to drive at night, take a bleedin' cab. I've got frickin' flash-burn from those things. There's a silhouette of me burned into my seat from the radiation exposure caused by those things! I'm pretty sure they should be licensed as deadly weapons. If there are any beings on the planets of Proxima Centauri, I'm pretty sure they are wondering what the small star in orbit around our sun is, and why it keeps flickering so much!
Very good points, thank you Gizmo and Daniel! I forgot about LED driven monitors, oops. Happily one of my monitors is LCD. I could have LED light bulbs everywhere but refuse them. Which is a bit of apita and compact fluorescents are not as good or bright as they used to be. Seems true to me.
imho LED light bulbs are bad for your eyes because they emit too damn much blue. That's what I read at any rate.
That's actually NOT true, nor is that even remotely what the study says. LED bulbs emit no more or less blue than any other lighting device that produces that same color temperature of light. What the study says is that prolonged exposure to excessive amounts of blue light is damaging to the eyes. This fact is true REGARDLESS of whether it is produced by LED bulbs or a gas flame. The issue is that we can produce LEDs the emit ONLY blue, and it is very easy to get into a situation where you have cranked up the intensity of the LED to the point that you are damaging your eyes without even knowing it.
Again, the issue is NOT that LEDs inherently produce some kind of light that is instantly and permanently damaging. ANYTHING can produce this light, INCLUDING the Sun! The issue is that we are making LEDs that SPECIFICALLY emit blue light, and they CAN BE made to do so at intensities that can be damaging.
BTW, your LCD monitor has EXACTLY the SAME problem! So do the compact fluorescents. So does pretty much every light source. Under certain situations, even candles and kerosene lamps. Indeed, if you look at the Sun through a blue filter, you've got the same problem.
Look, don't take my word for it (as you obviously aren't). Go do some research on what ophthalmologists say (you know, the people who actually study eyes for a living).
Thanks for put my mind and eyes at ease>":O}
I bow to your superior knowledge. But at least I know that too much intensity of "hi freq" blue is dangerous. Sheeite, I'm already half blind.
George, I'm worried that you're stuck on this blue light thing.
It's not blue light specifically, or even "hi freq" blue light. Too high an intensity, at ANY frequency (red, green, blue, yellow, cyan, magenta, white, orange, grey, ANY color) is damaging. It doesn't matter if the wavelength is 380 nm or 700 nm, or anything in between.
Just to add to Gizmo's post above, any frequency of light, including some that our eyes' lenses can bend, but which we cannot perceive, is potentially dangerous. If you repeated the experiment described above with red or green light, the same effect would be present. The various militaries around the world have long toyed with the concept of infra-red or ultra-violet lasers being used as a non-lethal weapon to blind enemy combatants without giving your own position away.
Why blue LEDs are being picked on (and also phosphorescent light like CFL, CRT and so forth) is that while the eye responds best to ~420nm blue light with limited deviation, the commercially produced LEDs are ~450 to ~470nm. To get the same response, a higher intensity blue is needed. I've attached a quick paint-mash to illustrate this. It's easier to produce red/green LEDs that fall within the eyes sensitive range, because those ranges are so much wider than for blue.
Normally this isn't a problem, if you follow sensible screen habits, like taking regular screen breaks, spending regular time outdoors (where the environment is bathed in blue and ultraviolet light, but with differences in intensity and focal length that the eye is adapted to process), and moderating your diet, weight, smoking, alcohol intake, head trauma (boxers take note), avoid staring directly at the sun, arc welding and metal smelting, and don't let anyone point a laser pointer at you.
On the scale of risks to eyesight, blue isn't the only problem.
Ah, so. That's why the hipsters always wear dark glasses. But it's ALREADY so dark for most of the year in Seattle. I'm already stuck on many things, there's room to remove blue light from the list. Thanks for the clarification Gizmo and Kaitain!
I always thought that was due to the effect of cocaine on the dilation of the pupil
I'm sure that it is so far too often.
Cocaine. What plain terrible stuff. The stuff simply demands that one ingest more. Thank God I missed crack!
I find LED light bulbs to be very good.
My table lamp here is 2700 Kelvin (warm white), not blue at all that I'm aware of, and still going strong after 4.5 years.
I don't use any dimable LED bulbs because they flash very rapidly, but not sure if that is bad for you or not.
I can attest to the fact that incandescent light bulbs nowadays are made to die extremely quickly. Got eleven days burning time out of a 60-watt bulb that's under the range hood recently. And that was "running" all the time, no off and ons to strain it's poor widdle filament. They more often last for six weeks or so. Made in Hungary by GE, that wondrous corporation that used to bring good things to life- allegedly.
I don't know what 2700 degrees Kelvin means in the spectrum of light. How did you measure this quantity if I may ask?
Thank you for letting us know that dimm-able LED bulbs flash rapidly. Who knew?
The colour temperature relates to the frequency of light emitted by an ideal black body emitter at a specific temperature.
In more human terms - you know when you heat metal and it glows red hot, then white hot? If it didn't melt, it would eventually glow blue hot. Ironically, "cold" colours are hotter than "warm" colours, as they're higher energy photons. An ideal black body emitter can be thought of as a material that stays roughly unchanged with temperature. If you heated that material to 2700K, it would emit light roughly the same colour as danrok's light bulb. If you heated it to about 5750K, you'd get sunlight which has less red, more blue and appears more yellow-white to human eyes.
This image gives you a good idea.
Why are you guys hanging out here? Shouldn't you be inventing fusion?
Thanks for elevating our discourse!! ":O}
Thank you very much for the "graph" danrok. It looks like 2700 Kelvin doesn't feature any blue. If I can find LED bulbs that put out 2700 K I think no one's eyes seeing it would be "over blued."
Which brings the thread full-circle.
A 2700K light has some blue. The LEDs most commonly made for blue don't quite match up with the human eye's sensing range for blue light, so a higher absolute intensity of blue is needed to create the right perceived intensity. Thus your eye may be receiving more blue than you expect. A highly artificial laboratory test involving causing rats to stare at a high intensity strobe light highlighted that optical cells were more greatly affected by blue than by red or green light, thus the scientists raised a concern over LED lighting.
It's worth remembering that researchers express similar concerns all the time, and that these have to be put into context. If you take the global population who went blind in later life due to one of the mechanisms suggested in the study (really, cataracts and/or macular degeneration) you might have a statistical risk of 0.067%* of going blind. Use of LED lights might increase that risk a little. Even if it doubles your risk - 0.13% is still a low likelihood of being affected, and you can safely ignore it.
* based on a very rough count of number of people reporting blind in the US multiplied by the fraction typically due to cataracts and macular degeneration, roughly a third, using numbers from wikipedia. It's just to illustrate that doubling a small risk is still a small risk.
Thanks Kaitain, this is useful and interesting information. I made my cataracts read this post, they feel good about their very slow growth now!
Separate names with a comma.